This invention relates to electrically powered toothbrushes and more particularly to such toothbrushes having a head which provides a three dimensional reciprocating side-to-side and rocking up-and-down motion.
Conventional electric toothbrushes having generally cylindrical brush heads operate by means of a direct current motor, wherein the rotational motion of the motor is translated into a two dimensional, typically, rotationally clockwise and counterclockwise reciprocating movement. As disclosed in U.S. Pat. No. 4,156,620, the unidirectional, axial motion of the drive shaft of a direct current motor, can initially be converted into a circular motion by means of a pinion and crown gear assembly. The circular motion can then be translated into a reciprocating motion to correspondingly drive the brush head by means of attaching to the crown gear a crank arm and clevis assembly. This is a complex mechanism, which is relatively costly to produce and has a high potential for mechanical failure.
U.S. Pat. No. 5,625,916 discloses a simplified electric toothbrush drive mechanism, wherein the end of the drive shaft is in the form of an elbow, i.e. bent away from and partially back toward its own longitudinal axis, and disposed within a slot in a cylindrical brush head; which slot is parallel to the longitudinal axis of the cylindrical brush head. As the drive shaft rotates unidirectionally, the elbow will describe a corresponding unidirectional circle about the longitudinal axis of the drive shaft, traveling up and down relative to the longitudinal axis of the cylindrical brush head, such that it drivingly engages the side edges of the slot to cause the cylindrical brush head to reciprocate side-to-side in two dimensions. Such a two dimensional reciprocating action limits the duration of contact between the bristle tufts and the three dimensional dentiture of the user, limiting the cleaning efficacy of the toothbrush.
U.S. Pat. No. 5,862,558 discloses a powered toothbrush head having a three dimensional motion, wherein the bristle ends rotate in a cone shape for enhanced cleaning. To achieve this three dimensional cone shaped rotation, U.S. Pat. No. 5,862,558 utilizes a complex mechanism involving two bearing pins (one transverse to the longitudinal axis of the toothbrush and the other angled thereto), a contrate gear and pinion assembly, and a tapered disk. Such a complex mechanism has the same failings as in the case of U.S. Pat. No. 4,156,620, discussed above, i.e. costly to produce and with a high potential for mechanical failure.
There is an ongoing need in the art for an electric toothbrush having a simplified mechanism and that provides a three dimensional head motion to conform the bristles more closely to the teeth for enhanced cleaning thereof.
The present invention provides a mechanically simplified electrically powered toothbrush having an elongated body with a head at one end and a handle at the other; the head containing a socket having curved sides; the socket containing a bristle carrier orbitally disposed therein; the bristle carrier having an upper surface with a plurality of bristle tufts extending therefrom and sides with a curvature corresponding to the curved sides of the socket; the bristle carrier being provided with a boring in the sides thereof; the handle being arranged to contain a rotational driving means with a drive shaft extending therefrom and ending in a end which is displaced from the central longitudinal axis of the drive shaft and is drivingly engaged in the boring; whereby, upon rotation of the drive shaft the bristle carrier is driven by the end in a three dimensional, reciprocating side-to-side and rocking up-and-down motion within the socket. This three dimensional movement of the toothbrush head increases contact between the bristles and the three dimensional surfaces of the teeth for enhanced cleaning thereof.